Geospatial Analysis and Vector Control for RiftValley Fever in Saudi Arabia

Abstract

Rift Valley fever (RVF) is a seriouslife-threatening diseasewith severe clinical manifestations and health consequences for humans anda wide range of domesticated animals. Human can be infected either by mosquito bites or through the exposure to blood, body fluids, or tissues of RVF-infected animals.In September 2000, a RVF outbreak was reported in Saudi Arabia, particularly in the Jazan region south-west Saudi Arabia with 886 human cases including 124 deaths.This outbreak has raised concerns about the potential spreading of the disease in new geographical areas including Europe, Asia and Americas as a consequence of climate change and globalization of trade in animals and animal products.Since the early recognition of RVF in Saudi Arabia, a comprehensive control program has been launched to contain the outbreak, albeit, the existing preventive measures are inadequate.However,these control measures are obviously lacking the geographical perspective besides the absence of spatial aspects. Furthermore, the geographical distribution of mosquitoes according to coordinates has not yet been adequately addressed.From these perspectives, the aim of thisstudywas (1) to examine the abundance and the distribution of RVF vectors according to geographical coordinates especially of the genus Aedes (2) toinvestigate the existence of RVFV in mosquitoes by molecular techniques.(3) to develop a new risk model to predictthe potential epizootic areas for RVF and the boundaries of intervention activities.4- to identify locations where people are potentially exposed to RVFand tocalculate the total population who are potentially exposed toRVF.However, various innovative approaches and novel bio-technological tools including, but not limited to, PCR, GIS (Geographical Information System) technology, GPS (Global Positioning System), satellite images,and field observation techniques were used in the current study. The results of thisresearch indicated that the very high risk zones were located in Sabia district, while both of Sabia and Balgazi districts were predicted as having high vulnerability to RVF occurrence. There are about 16.13 Km 2,of land under very high risk, 475.47Km

2 under high risk, and 3577.60 Km 2 under medium risk. Interestingly, at least 54315 persons in the cities of Samtah, Alardah, Alshigairy and Alaydabi are located nearby mosquito breeding sites and much more likely to have mosquito-borne diseases.Regarding mosquito surveillance data, Culex species was consistently the predominant mosquito, ranged from 98.13% to 99.26% in Sabia and Abuareesh respectively. While, phlebotomus sandflies, were found sporadically distributed in all districts with high relative abundance in Bulgazi (5.6%). Moreover, all mosquito samples tested by RT-PCR for the presence of RVFV were reported as negative.

The outcome of this study could enhance the existing RVF surveillance and preventive measureseffectively over the long time as well asenable decision makers to focus limited resources on areas at high risk of the disease.